First off I just wanna say: thanks for taking the time to make this mod. I think vehicles and just more complex combat in general is the biggest thing Factorio lacks. Airplanes should be part of vanilla tbh.

For those of us who want to have airplanes earlier, consider giving us a "space age easy mode" option that reverts technology and ingredients to vanilla values. I'd say this mod is overall exactly as balanced the old version was when running Space Exploration but it would still be nice to have that option.

I've looked at it and here is what I came up for "space age easy" mode:
- jet research needs up to space science, but it's not a valuable enough vehicle to need any more grinding than that IMHO.
- The flying fortress it seems it should either need metallurgic science or agricultural but maybe not. The flying fortress is good but it's not that good.
- True Nukes + SE lets you get thermobarics with space science which are better than high explosive shells, so space age easy mode should let you have these with all the nauvis sciences and that's it.

Here I tested things out and came up with this:

https://pastebin.com/h4U6u3E1

Thank you for putting this together! I'm not the original creator of this mod, just the maintainer of this fork, but I am responsible for this mod's Space Age-specific changes. Looking at your code, I like the suggestions, but I believe that the best choice is to modify my existing code to disable certain lines when an "easy-mode" config setting is enabled, and to not use your code, which seems to have a lot of redundant lines. I'll put something together when I have time to implement your suggestions.

One thing that will make your suggestions more viable is to make new aircraft that are even better than the aircraft in this mod currently, changing the recipes for the flying fortress and jet to not require carbon fiber, but adding new aircraft that do require carbon fiber.

Since the Flying Fortress requires artillery in vanilla, it makes sense for it to require metallurgic science, but I can remove the need for agricultural science or carbon-fiber for all currently existing aircraft.